1. Field of the Invention
The present invention relates to a coin discriminating apparatus, in particular to an apparatus for electronically discriminating diameter of coins.
2. Related Art Statement
Hitherto, coin discriminating apparatus, have been known using a plurality of sensor coils arranged along a coin passage for discriminating material, thickness and diameter of coin by detecting a variation of an inductance which is generated in each of the sensor coils by a coin passing through the coin passage when a magnetic field generated by the sensor coil is crossed by the coin.
In such a coin discriminating apparatus, it is known to individually discriminate diameter and material of coin to obtain a high accuracy of discrimination. Thus, there have been known various means for electronically, mechanically or optically discriminating diameter of coin.
In case of electronically discriminating diameter of coin by means of sensor coil, it is required to use a sensor coil having a large diameter and an L. C. oscillating circuit connected to the sensor coil to detect the coin diameter by way of detecting a variation of oscillation frequency or oscillating voltage and consequently is expensive. In case of mechanically discriminating, there are disadvantages that a construction of the coin passage is intricated and the apparatus becomes large as the whole. In case of optically discriminating, there are disadvantages that counterfeit coins having a diameter increased by taping can not be detected and the arrangement of optical sensor is difficult.